23/
$t=3h=10800s$
$2NaCl+2H_2O\to 2NaOH+H_2+Cl_2$
$m_{Cl_2}=\frac{71.0,2.10800}{2.96500}= 0,795g$
$\Rightarrow n_{Cl_2}= 0,011mol$
$\Rightarrow n_{NaOH}=0,011.2=0,022 mol$
$m_{NaOH}=0,022.40=0,88g$
24/
$2MCl_n\to 2M+nCl_2$
$n_{Cl_2}=0,039 mol$
$2n_{Cl_2}= n.n_M$
$\Rightarrow n_M=\frac{0,078}{n}$
$M_M=\frac{3,12n}{0,078}=40n$ (Không có n thoả mãn)